1 of 5
In a speech for Sun Yat-sen's 160th birth anniversary, China's President called Taiwan an "unwavering historical mission" of the Communist Party, a week before he is due to meet Donald Trump.
Xi Jinping said on Thursday that Taiwan's "complete reunification" with China "will certainly be realised", and pledged to pursue it peacefully.
He did not mention the use of force, which China has never renounced; Taiwan's government did not immediately comment.
The speech comes a week before the APEC summit in Shenzhen, where Xi is due to meet Donald Trump, and two weeks before local elections in Taiwan.